An orthosis comprises a cervical portion that holds a head in place relative to a thoracic portion worn by a wearer. The orthosis has an intermediate portion disposed intermediate the cervical and thoracic portions. The orthosis also has a first adjustment region that provides at least 15° of relative movement between the cervical and intermediate portions, and a second adjustment region that provides at least 15° of relative movement between the thoracic and intermediate portions. First and second adjustment regions allow the orthosis to comfortably accommodate differently proportioned wearers, and each comprises one or more locking devices to prevent undesired movement of the cervical and thoracic portions relative to the intermediate portion.